A compressed cartridge heater of this type is known, for example, from DE 70 31 974 U. A plurality of heating conductor coils with different wire thicknesses and different coil diameters are accommodated in this cartridge heater concentrically with one another, exposed in a cylindrical cartridge housing, which has a fixed front-side bottom at one end and whose other end is closed by a metal disk with wart-like holes. Instead of the otherwise usual terminal screws, strands provided with insulating jackets are connected to the ends of the heating conductors. These strands are led through the metal disk toward the inside with their insulating jackets, so that there is an insulation between the metal disk and the conductor wires of the strands.
DE 197 16 010 C1 discloses an electric jacket tube heater with integrated temperature sensor, in which the heating conductor coils are installed in a hairpin-like pattern in the jacket tube and the connection of the heating conductor is led out at one end of the jacket tube and of the connection temperature sensor at the other end of the jacket tube. The heating coil is embedded in compressed insulating material.
No support elements, which ensure that when the insulating granular material is filled in, the windings of the heating coil will not come into contact with the tube wall, are provided whatsoever for the heating coils within the metal tube in these prior-art cartridge heaters. It must rather be ensured when the granular material is filled in that the heating coils will not be bent out and are kept away in space from the tube jacket.
This makes it difficult to fill in the granular material and causes high manufacturing costs.